//***********************************************************************
//	PP3_5.java 		Author:GK
//  
//	Calculate the distance between two points.
//***********************************************************************

import java.util.Scanner;

public class PP3_5
{
	public static void main(String[] args)
	{
	double x1,x2,y1,y2,d1,d2;

	Scanner scan = new Scanner(System.in);
	
	System.out.println("请输入x1,y1：");
	x1 = scan.nextDouble();
	y1 = scan.nextDouble();
	System.out.println("请输入x2,y2：");
	x2 = scan.nextDouble();
	y2 = scan.nextDouble();

	d1 = Math.pow(x2-x1, 2) + Math.pow(y2-y1, 2);
	d2 = Math.sqrt(d1);
	System.out.println("结果：" + d2);
	}
}
	
